It is currently common practice to use rigid screw type back stops in machine tools, dies, jigs and fixtures for the purpose of providing repeatable, accurate positioning of work pieces in a press while allowing stop adjustment to insure accurate positioning of the work pieces in the tool or fixture. In some instances, however, the required stop gauge position in the particular tool is such as to produce interference with mating parts of the machine tool during normal operation. In such cases the machine tool is usually modified to provide clearance for the stop gauge. In some cases there may be multiple locations of the stop gauge in order to accommodate different parts to be made or formed in the same machine tool. To that end multiple clearance slots may be required in the machine tool. This procedure is not only expensive, but materially reduces tool life. Such slots even can be dangerous if during the set up of the machine tool great care is not taken by the set up person to insure proper alignment of the stop gauges and mating tool clearance slots. If misalignment does take place in a press set up, for instance, more than likely there will be considerable damage to the accompanying tooling and possibly to the press, to say nothing of possible danger to the press operator or set up person.
There are many instances where even if there is not interference between the stop gauges and the production tooling, there is still the opportunity for operator error, particularly in piece work situations. For example, the operator may inadvertently place the work piece on top of or underneath the stop gauge. In that event, serious damage to the conventional rigid stop gauge and work piece is inevitable once the press or machine is actuated. Furthermore, risk of injury to the operator or damage to the machine tool is present. Accidents of the type briefly described above are costly, not only in down time and repairs, but in the risk of human lives and limbs.
It is a primary object of this invention to provide a simple, inexpensive, but highly effective stop gauge for machine tools that eliminates much of the cost and dangers associated with the commonly used standard screw type gauge system.
It is a further object of this invention to provide a stop gauge as set out in the immediate preceding object which embodies a basic concept readily useful in precision automated gauging systems with no loss of accuracy.
It is another important object of this invention to provide an improved back stop for machine tools which prevents extensive damage to an associated machine tool.